(1) Field of the Invention
The present invention relates to the field of storing and transferring fluids, in particular liquids.
The present invention relates to a removable coupling device for coupling together two flexible pipes (or “hoses”), said removable coupling device being more particularly designed to connect a fuel tank of an aircraft to a pipe, or else to interconnect two tanks of an aircraft.
The present invention also relates to a fuel storage system using such a removable coupling device for coupling together two tanks, and to an aircraft using such a fuel storage system.
(2) Description of Related Art
In aircraft, and in particular in rotary-wing aircraft, it is frequent to have a plurality of fuel tanks. Such tanks are generally flexible and are received in compartments separated by structural partitions. Such compartments and such structural partitions can be situated in a lower structure of the aircraft, e.g. under the floor of the cabin of the aircraft, or else in vertical structures of the aircraft, such as transverse or lateral walls.
In addition, such tanks can be connected together in order to enable fuel to flow. A connection between two tanks is often obtained by equipping each tank with a flexible pipe, the two flexible pipes then being coupled together. The coupling between the two pipes is generally situated inside one of the two tanks, the pipe of that tank being folded back towards the inside of the tank, while the pipe of the other tank passes through the structural partition of the aircraft separating the two tanks.
Such a coupling between two tanks or else between a tank and a pipe is described in Document FR 2 456 277. That coupling is achieved by securing together two pipes by means of a clamping collar, a metal sleeve being positioned inside the pipes in order to stiffen the coupling. In addition, the two pipes are pressed against each other without adhesive bonding.
It is also possible to lubricate the connection between the two pipes by using fuel. Such lubrication thus enables one pipe to slide a little relative to the other.
The flexible pipes are generally made of elastomer adapted to transporting hydrocarbons, and they can include reinforcements embedded in their walls.
In addition, in Document CA 2 176 822, a coupling between a rigid male cylindrical pipe and a female device is achieved by a quick connector including deformable means and rigid means. Tabs on the deformable means acts as axial abutments by co-operating with grooves in the female device. Two O-ring gaskets positioned radially between the male cylindrical pipe and the female device seal the coupling.
In addition, Document U.S. Pat. No. 7,878,550 describes a sleeve interconnecting two conduits, that sleeve having a flexible first end, a semi-rigid second end, and its middle portion optionally being flexible. Each end is fastened mechanically to a respective one of the two conduits, without being bonded adhesively.
Furthermore, a coupling between two pipes interconnecting two tanks of an aircraft must also withstand a certain intensity of impacts and crashes that might be suffered by the aircraft. Thus, the coupling between two pipes must be suitable for receiving impacts and must enable the pipes and/or the tanks to be displaced so long as such impacts and displacements are of intensity or amplitudes less than predetermined limits. Such impacts or such displacements must not cause the coupling to break and must not cause either of the pipes to tear.
To this end, the coupling between two pipes is freely movable so as to reduce the concentrations of the stresses that would form where it is situated during impacts and/or displacements.
In addition, access to this type of coupling, for fitting it, removing it, or maintaining it, is generally from the inside of the cabin, after a portion of the floor has been removed by opening an inspection orifice for inspecting the tank.
Fitting and more particularly removing such a coupling can be difficult and complex. The two pipes tend to stick together after the fuel used for lubricating the coupling has dried. There is a high risk of tearing at least one of the two pipes during such removal, so that a maintenance operation can result in at least one tank being destroyed.